Thyroxine (T4), total – DM6 Health


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Thyroxine (T4), total


What is Thyroxine (T4)?

Thyroxine, also known as T4, is a hormone produced by the thyroid gland that plays a key role in regulating the body's metabolism. It is involved in a variety of bodily processes, including heart rate, body temperature, and energy production.

Why is Thyroxine (T4) tested?

Thyroxine (T4) is typically tested as part of a thyroid function panel to evaluate the function of the thyroid gland. It may be ordered when a person has symptoms that may be related to an underactive or overactive thyroid, such as fatigue, weight gain or loss, or changes in heart rate.

How is Thyroxine (T4) tested?

Thyroxine (T4) is typically tested using a blood test. A healthcare provider will draw a sample of blood and send it to a laboratory for analysis.

What do the results of a Thyroxine (T4) test mean?

High levels of Thyroxine (T4) in the blood may indicate an overactive thyroid, or hyperthyroidism. Low levels of Thyroxine (T4) may indicate an underactive thyroid, or hypothyroidism. It is important to note that the interpretation of Thyroxine (T4) test results should be considered in the context of other thyroid function tests, such as thyroid-stimulating hormone (TSH), as well as the presence or absence of symptoms.

Can medications or other factors affect Thyroxine (T4) test results?

Yes, certain medications and other factors can affect Thyroxine (T4) test results. For example, certain medications, such as lithium, amiodarone, and steroids, can interfere with thyroid function and affect Thyroxine (T4) levels. It is important to inform your healthcare provider about all medications you are taking before having a Thyroxine (T4) test.

Is a Thyroxine (T4) test safe?

Yes, a Thyroxine (T4) test is generally safe. The test involves a simple blood draw, which carries a small risk of bleeding or infection at the puncture site.

Are there any clinical studies on the effectiveness of Thyroxine (T4) testing?

Yes, there have been numerous clinical studies on the effectiveness of Thyroxine (T4) testing for the evaluation of thyroid function. These studies have demonstrated the utility of Thyroxine (T4) testing in the diagnosis and management of thyroid disorders.


Mayo Clinic. (2021). Thyroid function tests. Retrieved from

Lab Tests Online. (2021). Thyroxine (T4) test. Retrieved from

National Institute of Diabetes and Digestive and Kidney Diseases. (2021). Thyroid tests. Retrieved from

American Thyroid Association. (2021). Thyroid function tests. Retrieved from